1. Field of the Invention
The present disclosure concerns the field of functionalised nanoparticles, their production and use.
2. Discussion of the Background Art
It is known how some organic molecules are able to be absorbed on surfaces of solid inorganic materials and this property has been widely used to the extent that entire classes of technologically important compounds have been formed, such as dispersants and “wetting agents”.
Some of these molecules not only are absorbed by the surface involved but also contribute to the formation of compact structures which may profoundly alter its properties.
Typical examples of organic molecules of the above type (defined here below as binders) are simple monofunctionalised aliphatic compounds such as thiols, sodium dodecyl phosphate, cetyl trimethyl ammonium bromide, various aliphatic phosphates and the phosphonic, carboxylic and hydroxamic acids.
Interaction usually occurs between the single functional group and the metallic inorganic surface leaving thereby free a simple aliphatic chain that is not able to interact in any way whit other functional molecules.
The affinity between the organic molecules and the surfaces depends on the chemical nature of each: these interactions have been studied for some very well-known cases, however a complete understanding of the affinities of the various binders with the surfaces of nanoparticles is still being discussed in the academic fields, since the results are often contradictory.
It is also known that nanoparticles are materials with dimensions smaller than 500 nm, or according to some authors smaller than 100 nm, which may form a stable dispersion in liquids if there is a repulsion potential between the individual units. No precipitation is observed in a dispersion because the intrinsic movement due to temperature prevents their being deposited by the effect of gravity. The potential of interaction between two particles depends above all on the surface status of the nanoparticle; this may be varied by absorption or by chemical binding with other molecular or ionic species present in the solution.
Some complexes composed of nanoparticles and monofunctional binders of the type mentioned above are known [see, for example, Aronoff, Y. G. et al. J. Am. Chem. Soc. 1997, 119, 259-262. Heimer, T. A.; D'Arcangelis et al. Langmuir, 2002, 18, 5205-5212; Yee, C. et al. Langmuir, 1999, 15, 7111-7115; Folkers, J. et al. Langmuir, 1995, 11, 813-824] but they present various disadvantages.
Besides the scarcity of materials and binders studied, the above-mentioned products are not soluble in a hydroalcoholic environment, a condition which is very important for biomedical and pharmacological applications. Moreover the simple aliphatic chain which remains free is absolutely not able to interact with the functionalities usually present in bioactive molecules.
On the basis of the above, it is clearly important to have complexes formed of nanoparticles and of functionalised binders which make them suitable for the various desired purposes, overcoming the above-mentioned disadvantages.